Lock assembly



March 10, 1970 l.. J. LAvlANA LOCK ASSEMBLY` Filed Nov. 24,

y INVENTOR r LAWRENCE .Lm/IANA 9v M 5f ATTORNEYS.

United States Patent O 3,499,209 LOCK ASSEMBLY Lawrence J. Laviana, Kensington, Conn., assignor to M. H. Rhodes, Inc., Hartford, Conn., a corporation of Delaware Filed Nov. 24, 1967, Ser. No. 685,549 Int. c1. Bzsp 11/00 U.S. Cl. 29-437 1 Claim ABSTRACT OF THE DISCLOSURE A corrosion resistant cylinder lock having a plug cornprising an injection molded acetal plastic core having a keyway and transverse slots for the tumblers, and a longitudinally slotted brass sleeve surrounding the core to provide the plug with longitudinal and circumferential strength.

BACKGROUND OF THE INVENTION Field of the invention The present invention relates to locks; more particularly it is an improvement in corrosion resistant cylinder locks.

Description of the prior art Cylinder locks of the wafer tumbler and pin tumbler types are well known. Plugs for such locks have been in expensively die cast, but die cast plugs have poor corrosion resistance. Corrosion resistant locks having brass plugs are known, but the plugs require intricate machining for the tumbler slots and keyway. Molded plastic plugs for locks have been proposed but are easily damaged or forced.

SUMMARY The cylinder lock of the present invention is easily fabricated and is highly corrosion resistant. An injection molded plastic core has a series of transverse slots for the tumblers and a longitudinal keyway. A cylindrical sleeve surrounds the plastic core to take up the stresses to which the plug is subjected, the tumblers extending through easily fabricated longitudinal slots in the sleeve to cooperate with the barrel in the normal manner.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. l is a longitudinal sectional view through the central axis of a lock cylinder assembly embodying the invention;

FIG. 2 is a sectional view taken on line 2 2 of FIG. 1; and

FIG. 3 is an exploded perspective view showing the parts of a plug assembly embodying the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings in detail, the present invention is illustrated in connection with a wafer tumbler type lock assembly 10, although pin tumbler type locks may be employed in connection with the present invention. The wafer tumbler type lock assembly illustrated in the drawings comprises a barrel having a cylindrical bore therein with a pair of diametrically opposed, longitudinally extending grooves 24 and 26 in the internal barrel wall along the cylindrical bore 25. Rotatably disposed within the cylindrical bore 25 is a plug 30. The plug is provided with a central longitudinally extending keyway 89 and a plurality, here shown as ve in number, of transversely extending passages 81, 82, 83, 84 and 85, in which are slidably mounted a corresponding plurality of tumblers 90. Each of the tumblers is provided with a pair of opposed locking tabs 95 which are movable into and out of the longitudinal grooves 24 and 26, and when disposed within said grooves will prevent rotation of the plug to effect a lock. However, the locking tabs are so proportioned that when the key suited for the lock assembly 10 is disposed in the keyway 89, the tumblers will all be so positioned by the notches on the key so that each of the locking tabs 95 of all of the tumblers will be clear of the grooves 24 and 26, whereby to permit rotation of the plug relative to the vbarrel 20.

As shown herein the tumblers 90 are biased in such directions as to move one or the other of their locking tabs into one or the other of the longitudinal grooves 24 and 26 to prevent rotation of the plug 30 relative to the barrel 20. As shown herein the biasing means are compression springs which are disposed between suitable abutments provided on the interior of the plug 30 and tab like protrusions 93 on the tumblers for biasing the tumblers as above stated. Of course, gravity type bias may be employed in lieu of the spring bias.

Previously, lock plugs have been constructed in a variety of ways. Some have been die cast from alloys of zinc, but such plugs are not suitable for outdoor use because they tend to corrode when exposed to varying ternperatures and high humidity. Noncorroding plugs have been made of brass, but because brass cannot be cast to the intricate slotted shape required, brass plugs can only be produced by a complex series of machining operations and are therefore expensive.

According to the present invention, the disadvantages of previous plugs are overcome by employing the present plug 30, which comprises an injection molded inner plastic core 80, surrounded by an outer metal sleeve 40. The core 80 is preferably molded from an acetal resin, but any other rigid, weather resistant plastic, such as nylon, acrylic, polyolen, phenolic or polyfluoroolen is suitable.

The core 80 is held within the sleeve 40 by a cap 50, which is preferably of chrome plated brass and is secured to one end of the sleeve. Within the core are tumblers 90, preferably of brass, biased resiliently by springs 100, preferably of corrosion resistant Phosphor bronze. The sleeve 40 is a hollow cylinder, preferably machined of brass or other strong corrosion resistant metal, with a pair of diametrically opposed, longitudinally extending slots 44 and `46, machined therein, of sufficient width to permit the locking tab 95 of the tumblers 90 to pass therethrough. One end 41 of the sleeve 40 is substantially open to receive the core 80 and bears a ilange 42 to which the cap 50 may be secured. In the illustrated embodiment, the opposite end 43 of the sleeve 40 is deemed a closed end in that it will not permit the passage of core 80 therethrough; it need not be solidly closed however. End 43 further comprises the threaded tip 49 for securing the plug 30 to latching means (not shown) and transmitting rotary motion thereto.

The core 80 is preferably an injection molded plastic cylinder preferably of a size to lit loosely within the sleeve 40. The core has a molded in central keyway 89 extending longitudinally therethrough and a multiplicity of molded in longitudinally spaced lateral passages 81 to 85. Each of the passages is of the proper size and shape to receive a tumbler 90 for slidable movement therewithin.

The cap 50 is shaped to cover the open end 41 of the sleeve 40 and may be secured thereto by tabs 53, which are bent inward to engage the flange 42. In the center of the circular face of the cap is a keyhole 59 aligned with the keyway 89 in the core 80.

In the illustrated embodiment using spring biased wafer tumblers 90, each passage comprises two passage portions, a rst passage portion 81a, 82a. 83a, 84a, 85a extending diametrically through the core and a second passage portion 8117, 82b, 83h, 84b, 85b communicating with the rst portion and extending from the surface of the core 80 to a blind abutment therewithin. As shown in FIG. 2, the abutment at the end of each second portion provides a seat or stop for one end of each compression spring 100. The body 94 of each tumbler 90 is slidable within the iirst portion, with the tumbler projection 93 extending into the second portion abutting the other end of the spring 100. Each spring 100, being compressed within the second portion of each slot between the abutment at the end of the second portion and the projection 93, biases each tumbler 90 toward the open end of the second portion, namely in an upward direction as viewed in FIG. 2.

In the illustrated embodiment, the adjacent passages and tumblers 90 are inverted, i.e. disposed at 180 with respect to each other adjacent passage and tumbler; thus, as viewed in FIG. 3, three passages 81, 83, and 85 have their second portions 81b, 83b, and 85h opening downwardly, while the other two passages 82 and 84 open upwardly. This optional arrangement permits a smaller core 80 to be molded with greater strength because the core 80 is more nearly symmetrical and is therefore not weakened by an uneven distribution of cutouts. However, according to the present invention it is not necessary for the core 80 to have great strength, because the outer metal sleeve 40 resists the forces applied to the plug.

It is obvious from FIG. 3 that the plug 30 may be assembled by inserting a spring 100 into each second passage portion 81b, 82h, 83h, 84h, 85h, inserting a tumbler 90 into each passage, inserting the core 80 into the sleeve 40 so that the locking tabs 95 protrude through the slots 44 and 46, respectively, and iinally placing the cap 50 over the open end 41 of the sleeve 40, aligning the keyhole 59 with the keyway 89 and bending the tabs 53 around the flange 42 to secure the cap 50 to the sleeve 40.

The tumblers 90 are conveniently shaped to cooperate with an appropriate key by inserting the key (not shown) through the keyhole 59 and into the keyway 89 to its seated position, and then grinding off the ends of the tabs 95 protruding beyond the sleeve 40. When the key is withdrawn, the tumblers return to their initial locked positions, being biased thereto by the expansion of the springs 100. Thus when the plug 30 is placed within the housing 20, as shown in FIGS. 1 a nd 2, a Working lock is assembled. In the assembled condition, the plug 30 is prevented from rotating with respect to the housing 20, as the locking tabs 95 of the tumblers 90 are biased by the springs 100 into a locked position so as to engage the grooves 24 and 26 of the housing 20. When a key is inserted into the keyway, the tumblers 90 are moved to the unlocked position, wherein the tabs 95 are retracted into the plug 30, thereby permitting rotation of the plug and the desired unlocking action.

It will be noted that most of the plastics from which the core 80 may be molded have a low coefficient of friction. Thus the tumblers 90 will slide smoothly and easily within the passages 81 to 85 between the unlocked and locked position, thereby providing smooth and positive tumbler action.

An important feature of a lock embodying the present invention is that it is highly resistant to tampering and forcing, even though it incorporates a plastic core 80 which has relatively low strength. The plug derives its strength from the metal sleeve and cap, which cooperate to resist any stress which may be applied to the plug.

Thus, if .one should attempt to force the lock by trying to rotate an object, e.g. the Wrong key, in the keyway 89,

4 the torque will be exerted on the keyhole 59 of the cap 50 and is thereby transmitted to the sleeve 40, which will resist the torque, as it abuts the locking tabs 95. Thus,

the plug of the present invention resists torque to about the same extent as a .one piece brass plug, because no substantial torque is exerted on the core 80. As a result, the lock is neither opened nor damaged when one tries to force it.

Similarly, any pressure on the front of the plug, ie., the cap 50, is transmitted directly to the metal sleeve 40, which resists such compressive force. Thus the core receives no longitudinal stress, and so the plug resists longitudinal stress with the strength of the metal cap and sleeve, even though the tumblers slide within passages in a separate plastic core 80 rather than passages machined in a one piece brass plug of the prior art.

From the foregoing it will be seen that the lock assembly described herein achieves the corrosion resistant advantages of a fabricated or machined brass lock assembly and the lcost advantages of a die cast zinc alloy lock assembly. By injection molding the plastic plug core 80 to form the longitudinally extending keyway 89 and the transversely extending tumbler passages 81 and 85, the intricate shape of the core is obtained in an inexpensive molding operation as is true in die cast materials. The cost of machining the brass sleeve 40 with its two simple diametrically opposed longitudinally extending slots 44 and 46 is small, and when the core 80 and sleeve 40 are assembled together with the cap 50, a plug 30 is achieved that is inexpensive, corrosion resistant, and yet which has high strength emanating from the enclosing sleeve and cap. Moreover, due to the nature of the plastic employed in forming the core 80, there is little friction between the tumblers 90 disposed therewithin and the plastic core, whereby to make the lock a smoothly acting lock requiring little or no lubrication throughout its years of use.

Having thusdescribed the invention, what is desired to be secured by Letters Patent and hereby claimed is:

1. The method of making a corrosion resistant tumbler type lock, comprising the steps of:

(a) injection molding a cylindrical plastic core with a longitudinally extending keyway and a plurality of diametrically extending tumbler passages therein;

(b) machining from brass a cylindrical sleeve with a Iclosed end and an open end proportioned to fit `around said core and having a pair of diametrically opposed longitudinal slots therein;

(c) disposing said plastic core within said brass sleeve by inserting said core through said open sleeve end with the ends of said tumbler passages in register with said slots in said sleeve; and

(d) then enclosing said core Within said sleeve by fixing a brass cap over said open sleeve end.

References Cited UNITED STATES PATENTS 1,550,435 8/1925 Ganz 70-375 1,741,093 12/1929 Briggs 70--367l 1,782,347 11/1930 Heyer 70-375 2,755,656 7/1956 Schwartz 70-364 3,186,199 6/1965 Schwartz 70-370 RICHARD E. MOORE, Primary Examiner ROBERT L. WOLFE, Assistant Examiner U.S. Cl. X.R. 70- 364, 375, 417 

